Components.AI: Implement explicit per-call tool display modes

### Is your feature request related to a problem? Please describe the problem.

Tool calls currently render nothing accidentally, and there is no explicit contract for built-in or custom presentation.

### Describe the solution you'd like

Support exactly three modes resolved per call: hidden by default, an opt-in collapsed built-in view showing name/arguments/result/status, or a custom renderer keyed by tool name. Update pending/running/succeeded/failed/cancelled state in place. Approval wrappers must still render when the underlying call is hidden.

### Additional context

Leaf task for #68227 requirements F11 and J7 and decision D14. Public API review is required.

See: https://github.com/dotnet/aspnetcore/pull/68333#issuecomment-5413299117

Start with parent issue #68227, requirements F11 and J7, and decision D14, then review the linked pull-request discussion. Confirm the public API for the three per-call display modes, state transitions, custom renderers, and approval wrappers. Done means each mode and pending/running/succeeded/failed/cancelled update behavior is specified and implemented.

Written by the indexing model from the issue text.